When New York started replacing its pay phones with wifi kiosks in January, the new free internet access was met with a great deal of excitement, particularly over the network’s speed. The beta launch included just a dozen wifi hubs, but the city plans to convert 7,500 phone booths over the next few years so that free wifi is as ubiquitous as the yellow taxi in New York. But now, concerns about privacy are beginning to emerge.

On Wednesday, the New York Civil Liberties Union (NYCLU) accusedthe city of using its new public wifi system, LinkNYC, to “build a massive database,” complaining that the company behind the program, CityBridge, can keep a vast amount of information about wifi users, per its privacy policy.